1 Department of Biodiversity Research, Global Change Research Centre, Czech Academy of Sciences, Brno, Czech Republic, 2 Faculty of Science, Institute for Environmental Studies, Charles University, Prague, Czech Republic, 3 Department of Agriculture, Yamagata University, Tsuruoka, Japan, 4 Biological and Environmental Sciences, The University of Tennessee at Chattanooga, Chattanooga, TN, USA, 5...

A defensive alliance in a graph is a set $S$ of vertices with the property that every vertex in $S$ has at most one moreneighbor outside of $S$ than it has inside of $S$. A defensive alliance $S$ is called global if it forms a dominating set. The global defensive alliance number of a graph $G$ is the minimum cardinality of a global defensive alliance in $G$. In this article we study the global ...

Abstract. We start with a (q, t)-generalization of a binomial coefficient. It can be viewed as a polynomial in t that depends upon an integer q, with combinatorial interpretations when q is a positive integer, and algebraic interpretations when q is the order of a finite field. These (q, t)-binomial coefficients and their interpretations generalize further in two directions, one relating to col...

The global forcing number of a graph G is the minimal cardinality an edge subset discriminating all perfect matchings G, denoted by gf(G). For matching M S⊆E(G)∖M such that G−S has unique called anti-forcing M. maximum among Af(G). It known hexagonal system equals famous Fries number. bipartite we show gf(G)≥Af(G). Next extend result to Birkhoff–von Neumann graphs, whose polytopes are character...